Process of producing pictures and photographic-printing plates.



WILHELM TRIEPEL, OF BERLIN, GERMANY.

PROGESS. OF PRODUCING PICTURES AND PHOTOGRAIHIG-PRINTING PLATES.

Specification of Letters Patent.

Patented Oct. 13, 1908.

Application filed September 3, 1907. Serial No. 391,266.

To all whom it may concern:

Be it known that I, WILHELM TRIEPEL, doctor of philosophy, a subject of the German Emperor, and residing at 59 F asanen strasse, in the city of Berlin, Germany, have invented certain new and useful Improvements. in Processes of Producing Pictures and Photographic-Printing Plates, of which the following is a specification.

The present invention relates to the know process of obtaining pictures and printing plates from colloidal films with the aid of bichromate, these films being brought into contact with pictures which consist of metals and which have been formed by direct exposure or development. I s

For executing the process, use is preferably made of the known reaction which provides the metals, for example, the metallic silver of a photographic copy, in a solution;

the latter substantially consists of alkali saltsof such acids the silver salts of which are insoluble in acids (haloid salts or sulfocyanids) and ferrieyanids, and, moreover, also contains bichromatesfor tanning the colloidal film. Such solutions or mixtures react, as is known, with the metals which are on the pictures, approximately according to the following chemical formula:

chromic acid (0 romate of chromic oxi-d) are formed which on their part have the capability of tanning colloidal substances.

Now in spite of the conversion of the silver into bromid of silver taking place almost instantaneously in the above mentioned reaction, I have nevertheless been -able to establish the fact that it is not possible to obtain pigment copies which are free from objection according to this known process, because the second stage of the re-action, that is to say, the reduction of the bichromate by the potassium ferrocyanid, requires a longer period of time, during which the potassium ferrocyanid difluses into the film and therefore fails to reduce the bichromate at the spots or places where it has formed. On the other hand I have found that when copies are thus obtained, the details ofthe original pictures do not remain when thepictures are developed, but that the pigmented gelatin floats away. If it is attempted, however, to remove this defect in known manner by an addition of alum and citric acid, flat pictures without sufficient depth are as a rule obtained, because when a small proportion of the bichromate is reduced by the potassium ferrocyanid, the gelatin which has been pre viously tanned by the'al-u'ni, receives another tanning to such a degree that its diffusing action is practically destroyed and the remaining potassium ferrocyanid cannot diffuse to greater depths and thus be permitted to re-act inthe denser portions of the silver copy. My attempts to remove these above mentioned defects have led to the result that this is quite possible whenI work as follows: Namely, I add to the known baths, the composition of which has been .described above, substances which influence 'catalytically the oxidation of the potassium ferrocyanid by bichromate, and hence the re-action of the latter, that is the tanning of the gelatin, to efi'ect oxidation of the potassium ferrocyanid in the places where it has formed. Thus the defects mentioned disappear at once.

As substances which have a catalytic action, I have found suitable the compounds of cerium, as well'as the raremetals of the earth, iron, uranium, cobalt, nickel, vanadium, titanium, thorium, manganese, mercury, copper, etc. as well as mixtures of the mentioned compounds.

In order that the process may be clearly understood, I give, the following example of one way of executing the same: If, in the first place, it is a question "of pictures, in the case of which gelatin carries the picture, socalled developing copies, I prefer firstly to tan these preliminarily in known manner, before I employ them for the present pigment process, and I treat them first in a bath which contains alum, formaldehyde and similar substances which have a tanning action, wash them well and dry them. I then soak the tanned or untanned pictures Well in Water again, and press them on a pigmented paper which is impregnated with a solution or mixture. mixtures about in proportions for which the following example may-be given, being pointed out that the relative quantlties of the individual chemicals may be varied within wide limits according to the effect which is to be obtained in each case. 2.0 grms.

.a picturesque tanning is effected, whereupon I compose these solutions or I potassium ferricyanid, 1.5 grms. potassium bichromate, 2.0 grms. potassium bromid, 0.4 grms. sulfate of the dioxid of cerium, 0.2 grms. nitrate of the sesquioxid of cerium, 100 c. cms. water.

In making a solution like the above, it is preferable to dissolve the salt of cerium by itself in some cold water, and to add this solution to the other chemicals. The quantity of the salts of the sesquioxid of cerium as well as the salts of the dioxid of cerium may also be increased if necessary. For the tungstate of sodium and the like, have a tanning action on gelatin, and to modulate their tannin action by adding inorganic or organic aci s, acid salts or alkaline compounds oforganic acids, which do not exercise a reducing action on the chromic acid, and which are suited to convert the metals which have a tanning action into a complex compound. Likewise, suitable quantities of readily volatile substances, as alcohol, acetone and the like, or also gylcerin and the like, may be added to'the sensitizing baths. The addition of these volatile substances increases the moisture absorbing properties of the surface.

For daylight copies, for example, those on celloidin paper, I have found suitable, among others, a solution which is composed approximately as follows: 2.0 grms. potassium ferricyanid, 2.0 grms. potassium bromid, 1.5 grms..

potassium bichromate, 0.2 grms. sulfate of dioxid of cerium, 0.2 grms. nitrate of ses'quioxid of cerium, 100 c. ems. water.

Instead'of the potassium salts employed in the foregoing examples, the corresponding sodium and ammonium compounds can, of course, also be employed. Further, the different components of the impregnating solutions may be allowed to act not only in their entirety, but also separated and in optional composition, partly on the silver print and partly on the pigment paper.

The pigmented paper, as long as it is pressed on to the silver copy, can be developed in hot water, or also the pigmented paper can be separated from the copy after sufficient contact under cold water, then transferred In the usual manner on to paper, glass,

metal, etc., and lastly developed. In order to obtain a pigment copy from a silver print in one of the two ways, a time of contact of from 3 to 5 minutes suffices generally speakm The faded copy which remains behind can be obtained again in the original strength by means of one of the usual developers and be used again in the same manner after it has been well washed.

If the development of the pigment print is proceeded with while the pigmented paper is in contact with the copy, it is preferable to liberate the finished picture in known manner from the compounds of silver which have formed, as well as from silver which has possibly remained unchanged, as, say, by thiosulfate, possibly with an addition of ferricyanids, for the purpose of avoiding darkening.

I have also found that when employing celloidin pictures, even when these are on fairly old paper, it is preferable in individual cases to soften these celloidin pictures previously in a solution of alcohol and glycerin, to which, if the copies still contain silver, haloid metals or other salts, for example, ammonium chlorid, which precipitate silver, are added. The addition of these substances is for the purpose of modifying the excess of soluble silver salts so that it no longer acts upon the sensitized solution, fixing being thereby rendered unnecessary. When strong solutions have been employed for impregnating the pigmented paper, it is preferable to remove the excess of the solutions by weak pressure.

The pictures and printing plates which are produced according to the above process with the help ofthe baths containing catalytic substances are specially remarkable for their more brilliant depths and more picturesque modulation, as compared with known pigment pictures obtained hitherto in a similar manner. Also the reproduction of even the finest details succeeds excellently. The production of pigment pictures, particularly fromdaylight copies, is particularly successful, although the quantities of silver which are contained in the film of the picture are only exceedingly small.

The individual chemicals which are employed for making the baths do not require to act in their entlrety on the colloidal film, but can'act, in optional composition, partly on the silver print and partly on the film. The process can be employed in all the methods of the art of reproduction which are based on tanning colloidal films by reproduction-products of chromates.

What I claim as my invention and desire to secure by Letters Patent is 1. -A process of producing pictures, photographic printing plates and the like from colloidal films, conslstlng 1n lmpregnatlng I mates a colloidal pigmented film with a solution containing haloid salts, ferricyanids, bichroan 'in-addition substances which act catalytically, in pressing a metallic picture formed by direct exposure which is to' be pigmented on to the impregnated colloidal stances which act catalytically, 1n ressing a metallic picture formed by dev opment which is to be pigmented on to the impregn-ated colloidal film,inseparating the picture and the film and in washing them.

3. A process of producing pictures, photo graphic printing plates and the like from colloidal films, consisting in impregnating'a colloidal pigmented film with a solution con:

taining haloid salts, ferricyanids, bichromates and in .addition substances which. act catalytically, in softening in a liquid which contains glycerin a metallic picture which is to be pigmented, 1n pressing the softened picture on to the impregnated colloidal film, in separating the picture and the film and in washing them.

4. A process'of v graphic printing plates and the hke from colloidal films in the case of unfixed silver copies still containing soluble silver salts, consisting in impregnating a colloidal iglnented film with a solution containing ha 01d salts, ferricyanids, bichromatesand 1n addi-' tion substances which act. catalytically, in

softening in a liquid which contains a salt which precipitates silvera metallic picture which 1s to be pigmented, in pressin the softened picture on to the impregnated colloidal film, in separating the picture and the film and in washing them.

5. A process of. producing pictures, photo-' graphic printing; plates and the' like from colloidal films, consistilrillgmin impregnating a colloidal pigmented with a solution containing haloid salts, 'ferricya-nids, bichroproducing pictures, photomates and in addition substances which act catalytically, in soaking in a liquid which contains glycerin and alcohol a metallic picture which is to be pigmented, in pressin the soaked picture on to the impregnate colloidal film, in separating the picture and the film and in washing them.

6. A process of producing pictures, photographic printing plates and the like from colloidal films, consisting in impregnating a colloidal pigmented film with a solution containing haloid salts, ferricyanids, bichromates and in addition substances which act catalytically, in soaking in a liquid which contains glycerin and alcohol a celloidin picture on rather old paper which is to be pigmented, in pressing the soaked picture on to the impregnated colloidal film, in separating the picture and the film and in washingthem.

7. A process of producing pictures, photographic printing plates and the like from colloidal films, co in impregnating a colloidal pigmented film with a solution containing haloid salts, ferricyanids, bichromates and in addition substances which act catalytically, in pressing a metallic picture formed by direct ezxposure which is to be pigmented on to the. impregnated colloidal film, in separating the icture and the film, in washing the colloidal lm, in transferring the latter to a, suitable material and in developing the film.

8. A process of producing pictures, photographic'printing plates and the likeefrom colloidal films, consisting in impregnating a colloidal pigmented film with a solution containing haloid salts, ferricyanids, blchromates and in addition substances which act catalytieally, in pressing a metallic picture formed by direct exposure which is to be pigmented-on to the impregnated colloidal film, and-in developing the film on the metallic print- In testimony whereof I have hereunto set my hand in presence of two SllbSCI'lblIlg wltnesses. v

WILHELM TRIEPEL Witneesz HENRY Hasrmz,

An'rmm Scnnonnnn. 

